<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>

let arr = [5, 8, 9, 2, 1, 5]
let sum = 0
for (let i = 0; i < arr.length; i ++) {
    sum += arr[i]
}
document.write(`数组元素的和为：${sum}`);

  </script>
</body>
</html>